1. Field of the Invention:
The present invention relates to an apparatus for controlling an air-mix door in an automobile air-conditioner.
2. Description of the Prior Art:
There are known various apparatus for controlling an air-mix door in an automobile air-conditioner to condition air at a temperature coincident with a desired target value before the air is discharged from an outlet of the air-conditioner. One such known air mix door control apparatus includes, as shown here in FIG. 4, target discharge air temperature calculation means 200 for calculating a target discharge air temperature based on a set temperature, a vehicle compartment temperature and an outside air temperature, actual discharge air temperature calculation means 800 for calculating an actual discharge air temperature being discharged from an outlet based on a temperature of air detected by a mode sensor 25 at a position downstream of an evaporator 8 and an output from a position sensor 100 for detecting the position of an air-mix door 12, comparator means 600 for comparing the target discharge air temperature with the actual discharge air temperature, and drive control means 700 for actuating the air-mix door 12 according to a result of comparison by the comparator means 600.
With this construction, the actual discharge air temperature is fed back to the comparator means for comparison with the target discharge air temperature. Since the response speed of the actual discharge air temperature is very low, the air-mix door 12 is controlled to move slowly in harmony with a change in the actual discharge air temperature and hence is likely to cause hunting. A stable control of the air-mix door 12 is therefore difficult to achieve.